Adding a belly tank on my 1985 Starcraft need freeboard & stringer advice

[castingcouchcaptain22]

I'm in the process of upgrading my 1985 Starcraft fishing boat, and I'm looking to add a belly tank to improve weight distribution with my new outboard setup.

The stringers measure about 4 inches in height, and the freeboard from the floor up to the gunwale is approximately 34 inches. The belly tanks I've come across require a minimum depth of 10 inches, so I'm trying to figure out whether I need to elevate the stringers or find a custom tank that's shallower.

Has anyone here tackled this on a Starcraft or a similar aluminum boat? I'd really appreciate any advice on how you managed the stringers and the tank fit. Thanks!

 

[ch!m!_ch@]

@castingcouchcaptain22 Honestly, for a 1985 Starcraft with those stringers, a custom shallower tank is usually the way to go.
Trying to raise your stringers significantly means a much bigger structural job, raising your entire floor, and potentially messing with your freeboard.
A good aluminum fabricator can build a tank that fits your exact under floor dimensions perfectly, even if it means a slightly wider or longer footprint for the same volume. It's often cleaner and less invasive than re engineering your main deck support

 

[Voyager]

Adding a belly tank to an old aluminum Starcraft is flirting with overengineering. These boats were never designed with complex fuel systems in mind, and modifying stringers for a tank could compromise structural integrity. Sometimes chasing modern upgrades just turns a great classic into a patchwork of regrets.

 

[emerie zaiya]

Hello, congratulations on your decision to upgrade your yacht. It's a wise choice to adjust the weight distribution with the bottom fuel tank.
Your stringers are 4 inches tall, and the belly tanks you’ve seen need a minimum 10-inch depth. So, you’ve got two solid paths here: either elevating the stringers (just make sure you use marine-grade plywood or aluminum supports that can handle the load and won’t rot/corrode) or hunting down a custom shallower tank. For the custom route, check with local metal fabricators who work with marine aluminum—they can often build a tank to your exact specs.
Since you’re working with an aluminum boat, also keep an eye on how the tank mounts to the hull and stringers—you want to avoid any galvanic corrosion, so use zinc anodes or isolation washers where metal meets metal.
Here is an article about "Yacht Trouble? 7 Common Part Problems & Repair Guide" delves deeply into the maintenance of ship components. Even if your boat is relatively small, some principles regarding hull integrity, hardware maintenance and weight distribution still apply. Perhaps this article can offer you some help during the process of installing your abdominal fuel tank!
Hope this helps—let us know how the project goes!

 

[Alan]

Hey @castingcouchcaptain22, nice project! With your 4-inch stringers, maybe try a custom shallow belly tank. It keeps the floor intact and avoids messing with freeboard.

If you try raising the stringers, just make sure any supports are solid and corrosion-resistant. Do you have a local fab shop that works with aluminum, or are you thinking of DIY?